نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه گیاهپزشکی، دانشکده کشاورزی، دانشگاه شهید باهنر کرمان، کرمان، ایران
2 گروه گیاهپزشکی، دانشکده کشاورزی، دانشگاه محقق اردبیلی، اردبیل، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Extended Abstract
Introduction
Pistachio (Pistacia vera L.), is a small tree native to Iran and Central Asia, grown for its edible seeds. The pistachio nut is an important export product and has a special value among agricultural products. The pistachio psylla, Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera, Psyllidae), is one of the key pests of pistachio trees. It is distributed in Turkey, Greece, Iran, Armenia, and Tajikistan. In both adult and nymphal stages, it directly damages trees by absorbing plant sap. Moreover, psyllids are usually involved in the transmission of pathogens and cause significant losses to the host.
In recent years, researchers have been interested in finding efficient and environmentally friendly methods to prevent biotic agents that damage plants, such as the application of potential ISR elicitors. Natural or synthetic elicitors make induced systemic resistance (ISR). The stimulation of the same plant defense mechanisms by specific inducing agents (elicitors) is an alternative tool to protect plants against pests. Elicitors can influence the secondary metabolite contents in plants in response to herbivores and induce defense mechanisms, thereby increasing the resistance of plants against pests. Further, secondary metabolites can affect oxidative stress through producing free radicals and modifying the antioxidant enzyme systems. Catalase and peroxidase enzymes play an important role in the defense system of plants. Thus, the present research was conducted to evaluate the effects of chitosan, gamma-aminobutyric acid and potassium silicate on the contents of secondary metabolites and biochemical compounds in pistachio leaves and the resultant effects on pest population control.
Materials and Methods
The field experiments were conducted on 30-year-old pistachio trees (cv. Fandoghi) in a 1-hectare orchard located in Najaf Shahr, Sirjan, Kerman, Iran during 2023. In this research, the effect of various compounds including chitosan (0.5%), potassium silicate (2%), and gamma-aminobutyric acid (GABA) (10 mM) were studied on the population reduction rate of pistachio psyllid nymphs in field conditions. The distilled water was applied as control treatment. Furthermore, the amount of enzymatic and biochemical compounds including antioxidant enzymes (catalase and peroxidase), hydrogen peroxide, proline, total phenol and flavonoids in the leaves of the treated pistachio trees were determined. Finally, variables evaluated using the one-way analysis of variance in SPSS. Then, the Tukey test was done for mean comparisons.
Results and Discussion
In this study, spraying various compounds, especially chitosan on pistachio trees, reduced the population of psyllid nymphs. The control efficiency (%) of studied inducers showed an increasing trend in treatments of GABA (23.76%), potassium silicate (34.39%) and chitosan (46.23%), respectively.
In our study, no significant difference was observed in the flavonoid contents among different treatments. Indeed, the level of total phenol in the chitosan treatment was significantly higher than others. Therefore, the difference in the control effect percentage of psyllid nymph population between the tested treatments can be related to the presence of phenolic compounds and other secondary metabolites. Some studies have proved a negative correlation between the presence of phenolic compounds in the host plant and the population of insects. On the other hand, pistachio trees treated with different compounds in terms of hydrogen peroxide, proline, enzymes of catalase and peroxidase showed a significant difference. The highest amounts of catalase and peroxidase enzymes were significantly observed in trees treated with chitosan (1.73 and 0.031, respectively). Peroxidase and catalase enzymes are important antioxidants which destroy free radicals. Also, the highest and lowest amount of proline was significantly recorded in the control (52.48) and chitosan (42.40) treatments, respectively. In addition, the amount of hydrogen peroxide in the GABA treatment (128.71) was significantly higher than other treatments, which related to the peroxidase enzyme (0.016) decrease in the plant. Peroxidase enzyme is activated by biological stress and plays an important role in protecting the cell against different toxic concentrations of hydrogen peroxide.
The findings of this research showed the lower population of psyllid nymphs in chitosan treatment was related to the higher relative content of phenol and more activity of antioxidant enzymes (catalase and peroxidase) in pistachio trees.
Conclusions
This study showed that treatment of pistachio trees with different plant resistance inducers, especially chitosan, causes physiological changes in the plant and subsequently the reduction of pistachio psyllid damage. After complementary tests on the quality and quantity of the product, these compounds can be used in integrated management programs of A. pistaciae to minimize the use of insecticides.
Keywords: Antioxidant enzymes, A. pistaciae, Control effect, Inducer, Total phenol
کلیدواژه‌ها [English]
)
ارسال نظر در مورد این مقاله